QUOTE (MikeKozar @ Dec 9 2009, 09:50 PM)

It would be reasonable to assume the system would flag a duplicate login, either denying access to the new user or booting the old one.
deny the new one entry
QUOTE
p110 Unwired
Copied Agents and IDs
Note that when an agent program is copied, the access ID
built into the agent is copied as well. This means that any copies
of the agent will have the same access ID. This is not a problem
when a hacker is running such copies simultaneously from his
persona (as his access ID is used in that case), or if the copies are
operating autonomously in independent nodes. If a copy tries
to access a node on which an agent with the same access ID is
already running, however, the node will automatically refuse ac-
cess (even if the agent tries to hack his way in, the attempt
will automatically fail). This security feature both deters
piracy and prevents mass invasions by agent mooks (the
so-called “Agent Smith” scenario).
A copied agent may be patched in order to give it a
separate unique access ID with a Logic + Software (Rating
x 3, 1 week) Extended Test.
I believe the same can be assumed for all access IDs as there is no real distinction between an agent's ID and a persona's other then it's origin.
QUOTE
p225 SR4A
Authorization and Authentication
In order to allow you access to anything beyond a public account, the
node must be given three things. The first is your access ID, which
is automatically given when you log on. Second, the node must have
your access ID associated with an access level/account privileges (for
example, your soycaf dispenser will have your access ID on a list that
shows that you have an admin account on its node); this is called authorization.
Third, you must have some way of proving you are the
person who has the authorization in question; this is authentication.
There are a number of methods a node can employ to authenticate
users. For low-security nodes like can openers or corporate restrooms,
the access ID alone is enough.
A node could demand a basic passcode before permitting entry.
Basic passcodes consist of sets of symbols that you enter to log on to
a node. The most common passcodes are alphanumeric strings, but
thanks to augmented and virtual reality, passcode “symbols” can...
Basically as I read this, to get into someone else's account, even if obtained by social engineering, you have to first spoof your Access ID to match, otherwise it's like trying to log in with the wrong username. I figure most groups probobly don't even bother with the Hacking + Software(2) test when doing this and just assume they log in with that ID. However this makes it so that if that user is currently on the hacker can't log in, or if the hacker is in the actual user can't log in. A fun thing to play with really.
User: "Hey, is this tech support? I seem to be having trouble logging in. I'm using the right password and everything."
Security Spider: "Whats your Access ID sir?"
User: "1234567890"
Spider: "According to this you're already logged in."
User: "Well I'm NOT."
Spider puts user on hold to check it out.